torrvolym

Torrvolym is a forestry and timber industry term referring to the oven-dry volume of wood. It represents the volume of timber when all free moisture has been removed, effectively at zero percent moisture content. Torrvolym is used as a standard reference state to compare wood species, assess density, and facilitate conversions between mass and volume.

Measurement and concept: Torrvolym is typically determined by oven-drying wood samples at a standard temperature (commonly around 103°C) until constant weight is reached. The final volume of the dry wood is then used as the torrvolym. Because wood shrinks as it dries, the torrvolym is generally smaller than volumes measured while the wood contains moisture (green or air-dry volumes). In practice, producers and researchers may estimate torrvolym from green volume using species-specific shrinkage coefficients.

Uses: The concept provides a uniform basis for evaluating wood properties, such as density and structural capacity, and for price calculations and inventory planning in the timber trade. It also enables consistent comparisons of different species and forms (roundwood, sawn timber, and industrial wood) by removing moisture variability from volume measures.

Relation to moisture: Torrvolym is specifically tied to a 0% moisture content. In service or market contexts, actual volumes reflect moisture content, thermal treatment, and anisotropic shrinkage, so conversions between torrvolym and moist volumes require appropriate corrections.

Etymology: The term is Swedish for “dry volume,” combining torr (dry) and volym (volume). It is used primarily in Nordic forestry literature and industry.